The present invention relates to an apparatus for continuously measuring the degree of milling of grains, typically of rice grains.
Generally, rice grains are milled by use of a whitening machine to remove bran thereby increasing the degree of whiteness of the rice grains. Conventionally, the grades of this whiteness have been noted as an indication of the degree of milling of rice grains. In the conventional devices for measuring the degree of whiteness, a tray on which the grains to be inspected are placed is positioned at the lower portion of an integrating sphere formed with an inner mirror surface, the grains are illuminated from an upper part of the integrating sphere by light transmitted through an infrared filter and a monochromatic light filter and condensed by a condenser lens, and the reflected light from the grains is collected at a light receiving element disposed at a side portion of the integrating sphere. The current generated by the reflected light receiving element is amplified by an amplifier and measured as the degree of whiteness of the grains.
There are two types of rice whitening machines, one being of a grinding type and the other being of a friction type. When the milled rice grains are examined with the unaided eye, those well milled by the friction type machine are found to be superior in their translucency and polish to those well milled by the grinding type machine. This results from the fact that, whereas the grains milled with the grinding type apparatus have scarred and rough surfaces due to the grinding action of the grinding roll against the grains, the surfaces of those milled with the friction type machines are smooth because the milled is effected by the mutual rubbing action between the grains being milled.
In the conventional degree of whiteness measuring apparatus, since the light reflected from the grains is measured and used as the degree of whiteness, there is a tendency that the grains with rougher surfaces which produce a greater diffused reflection indicate a higher degree of whiteness than the grains with smoother surfaces even if both the grains have the same degree of milling. This is because the amount of the light transmitted through the grains with smoother surfaces is greater than the amount of the light transmitted by the grains with rougher surfaces. Thus, with the conventional method of measuring the degree of milling which is based on the degree of whiteness, it is not possible to accurately determine the value of the degree of milling because the smoother the surfaces become the greater the light transmission ratio is as compared with the light reflection ratio.
Noting the above problem, we have previously proposed and disclosed in Japanese Unexamined Patent Publication No. 77637/83 laid open May 11, 1983, an apparatus for continuously measuring the degree of milling of rice grains with an improved accuracy, in which the degree of milling was measured based not only on the light reflected from but also on the light transmitted through the grains and the degree of milling was obtained based on both the factors. This apparatus enabled continuous measurement of grains by making the grains flow through a grain passage unit and the degree of milling was continuously measured there.
However, in the previous apparatus, since the grain passage unit included a vertical passage way, the grains flowed through the passage way in disorderly and irregular manner and thus because of irregularities and inconsistencies in the value of the reflected light it was not always possible to obtain an accurate value for the degree of milling.
The previous apparatus referred to in the foregoing in which the value calculated in an arithmetic unit based on the amount of the reflected light and the amount of the transmitted light was used directly as the degree of milling had a drawback in terms of reliability of the measured data, the drawback stemming from the fact that each measurement was for each given time of calculation, since the amount of reflected light from a reflected light detecting unit and the amount of the transmitted light from a transmitted light detecting unit change from time to time as shown in FIG. 4 and may be affected by various conditions such as the variation in the amount of grains fed at any one given time.
One object of the present invention is to provide an improved apparatus for continuously measuring the degree of milling of rice grains by which a more accurate value of the degree of milling can be obtained by positioning the grain passage at an appropriate angle to make the grains flow in the best condition.
To this end, the present invention provides an apparatus for continuously measuring the degree of milling of rice grains including a light source unit, a grain passage unit, a reflected light detecting unit, a transmitted light detecting unit, an arithmetic unit and a degree of milling meter wherein one wall of the grain passage unit is positioned angularly so that grains in contact with the wall slide down with their lengthwise axes oriented generally parallel to the wall surface and another wall is positioned so that the grains introduced and filled in the grain passage unit flow without a gap between this wall and the grains.
Another object of the present invention is to provide a further improved apparatus for continuously measuring the degree of milling of rice grains which diminishes irregularities in the measured values and in which the integrated value of the degree of milling is obtained by having the continuously flowing grains measured over a given period which period is divided into as many as several tens or several hundreds of divisions and the integrated data thus obtained is averaged to calculate the degree of milling being sought.
Thus, the present invention also provides an apparatus for continuously measuring the degree of milling of rice grains including a light source unit, a grain passage unit, a reflected light detecting unit, a transmitted light detecting unit, an arithmetic unit, a degree of milling meter, a first integrated data take-up unit and a second integrated data take-up unit wherein the first integrated data take-up unit and the second integrated data take-up unit are connected to the degree of milling meter through the arithmetic unit, so that the integrated data obtained in a given period divided into a number of divisions is averaged to calculate the degree of milling being sought.